1. Field of the Invention
This invention relates generally to optical projection systems and more particularly to optical projections systems such as in flight simulators that utilize Schlieren type light valves and have a means to correct for longitudinal chromatic aberration that may be caused by projection of the spatially separated colors generated by the light valve.
2. Brief Description of the Prior Art
In Schlieren type color projection systems, the aperture or pupil of the light valve consists of spatially separated colors that comprise an image. In projection systems such as used in flight simulators wherein the image from the light valve must be relayed through multiple lenses before final projection or focus on a screen or dome, the Schlieren image generated at the pupil of the light valve may be distorted when it is finally focused. This distortion is commonly realized as a longitudinal distortion such that the spatially separated colors of the Schlieren pupil are not focused at a common image plane at the final projection stage. Any one of the spatially separate colors may have a focused image offset from the desired plane. As the image is relayed through multiple lenses in the projection system the distortions increase with each cascaded section.
It is an object of this invention to Provide a simpler, more efficient way to apochromatize the Schlieren image by bringing the wavelengths of the spatially separate colors to a common focus. Another object of this invention is to provide an apparatus for correction of aberrations at any aperture stop in a complex optical train.